This project is part of a program project directed toward assessing cardiac effects of particulate and other ambient air pollutants. In this project patient who have recently suffered a cardiac event are being monitored with cardiac monitors for 24 hours up to 4 times during the year following their cardiac event. Similarly a second group of patients with moderate to severe heart failure will undergo similar cardiac monitoring for 24 hours, twice a week separated by 3 months. In both sets of patients home indoor pollution measures will be continuously made and used to correlate with measures of heart rate variability.